The problem arises in various fields of pattern recognition of having to make use of multidimensional feature vectors whose individual components, the features, are relevant in different ways in the case of different patterns to be recognized. This situation occurs, in particular, in automatic speech recognition, in which when previous recognition systems are used it is easy for phonetically similar words, (for example, German words "zwei" and "drei") to be confused. It is particularly easy when using known recognition systems to confuse words which differ only in a single phoneme (for example, German phonemes "dem" and "den"). This problem becomes still more acute in the case of speaker-independent recognition of speech which is carried over telephone lines, because due to the reduced transmission bandwidth of 3.4 kHz speech-relevant frequency ranges are lost (for example, The sounds /s/ and /f/ can no longer be distinguished over the telephone).
Some of these known recognition systems are based on a direct pattern comparison of stored reference words and the actually spoken word, with account being taken of temporal fluctuations in rate of speech. These fluctuations are taken into account with the aid of dynamic programming, for example. Moore has proposed an approach for such recognition systems (R. K. Moore, M. J. Russel, M. J. Tomlinson, "The discriminative network: A mechanism for focusing recognition in whole word pattern matching", IEEE International Conference on Acoustics, Speech and Signal Processing, pp. 1041-1044, Boston, 1983, ICASSP), which automatically finds the discrimination-relevant parts of words and weights these more strongly by comparison with the other parts. A disadvantage of this method is that the automatic search of discrimination-relevant parts can be affected by errors in the case of confusable word pairs. Discrimination-relevant word parts are not always found, or word parts are wrongly regarded as discrimination-relevant. This problem also cannot be solved in principle using the method of dynamic programming alone.